For a Hugo site, this could be pulled at build time using getJson right? But it would have to pattern match the URL with the post URL and then pull the relevant value. To happen on pageload, you'd have to make it a javascript snippet right?

It could be pulled at build time. This might make sense if you build the Hugo site often enough, like daily, otherwise the counts will drift and appear stale.

I can alter the stats.json schema to provide additional fields if needed in your implementation. I don't use Hugo myself so if you want to work on this, I'll hook you up with a Pro bono Production Remarkbox account.